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Message-ID: <1456975950.4044.92.camel@perches.com>
Subject: Re: about get_maintainer.pl not showing the original author of the
 modified code
From: Joe Perches <joe@perches.com>
To: Jianyu Zhan <nasa4836@gmail.com>, LKML <linux-kernel@vger.kernel.org>
Date: Wed, 02 Mar 2016 19:32:30 -0800
In-Reply-To: <CAHz2CGUwWchcK+6nKcwbiETku5zBP7AuF0HqAmk5j-9=KnwTFQ@mail.gmail.com>
References: <CAHz2CGUwWchcK+6nKcwbiETku5zBP7AuF0HqAmk5j-9=KnwTFQ@mail.gmail.com>
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On Thu, 2016-03-03 at 11:00 +0800, Jianyu Zhan wrote:
> Hi, Joe,
> 
> recently in this patch https://lkml.org/lkml/2016/3/2/281,
> 
> I found the original author of the modified code was not
> suggested as a patch reviewer.
> 
> This surprised me at first.??But later I realized that it is not trivial
> to define "original author", since the last modification might be
> just code polishing.??To dig out the original author, we might need
> go up the commit history and git must be equipped with ability of pattern
> recognization to analyze code.
> 
> What do you think?

There are many options to the get_maintainer script.
You can see all of them with "./scripts/get_maintainer.pl --help"

Many are not enabled because run-time can be very long as
running various git commands can take awhile to complete.

$ ./scripts/get_maintainer.pl --git-blame <patch|-f <file>>

with your patch get_maintainer.pl and --git-blame gives:

$ ./scripts/get_maintainer.pl ~/1.diff --git-blame
Thomas Gleixner <tglx@linutronix.de> (commit_signer:20/19=100%,authored:7/19=37%,added_lines:73/248=29%,removed_lines:38/119=32%)
Peter Zijlstra <peterz@infradead.org> (commit_signer:3/19=16%,authored:1/19=5%)
Andrew Morton <akpm@linux-foundation.org> (commit_signer:3/19=16%,modified commits:2/3=67%)
Davidlohr Bueso <dave@stgolabs.net> (commit_signer:3/19=16%,authored:3/19=16%,added_lines:113/248=46%,removed_lines:20/119=17%)
Ingo Molnar <mingo@kernel.org> (commit_signer:2/19=11%,modified commits:2/3=67%)
Dominik Dingel <dingel@linux.vnet.ibm.com> (authored:1/19=5%)
Jann Horn <jann@thejh.net> (authored:1/19=5%)
Sebastian Andrzej Siewior <bigeasy@linutronix.de> (added_lines:29/248=12%)
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> (added_lines:14/248=6%,removed_lines:49/119=41%)
Darren Hart <dvhart@linux.intel.com> (modified commits:1/3=33%)
Stephen Hemminger <shemminger@linux-foundation.org> (modified commits:1/3=33%)
Christian Borntraeger <borntrae@de.ibm.com> (modified commits:1/3=33%)
linux-kernel@vger.kernel.org (open list)

vs

$ ./scripts/get_maintainer.pl ~/1.diff
Thomas Gleixner <tglx@linutronix.de> (commit_signer:20/19=100%,authored:7/19=37%,added_lines:73/248=29%,removed_lines:38/119=32%)
Davidlohr Bueso <dave@stgolabs.net> (commit_signer:3/19=16%,authored:3/19=16%,added_lines:113/248=46%,removed_lines:20/119=17%)
Peter Zijlstra <peterz@infradead.org> (commit_signer:3/19=16%)
Andrew Morton <akpm@linux-foundation.org> (commit_signer:3/19=16%)
Ingo Molnar <mingo@kernel.org> (commit_signer:2/19=11%)
Rasmus Villemoes <linux@rasmusvillemoes.dk> (authored:1/19=5%)
Darren Hart <dvhart@linux.intel.com> (authored:1/19=5%)
kbuild test robot <fengguang.wu@intel.com> (authored:1/19=5%)
Sebastian Andrzej Siewior <bigeasy@linutronix.de> (added_lines:29/248=12%)
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> (added_lines:14/248=6%,removed_lines:49/119=41%)

running git blame alone gives:

$ git blame -L1927,+8 kernel/futex.c
^1da177e (Linus Torvalds????????2005-04-16 15:20:36 -0700 1927)?
^1da177e (Linus Torvalds????????2005-04-16 15:20:36 -0700 1928)?????????/* In the common case we don't take the spinlock, which is nice. */
42d35d48 (Darren Hart???????????2008-12-29 15:49:53 -0800 1929) retry:
^1da177e (Linus Torvalds????????2005-04-16 15:20:36 -0700 1930)?????????lock_ptr = q->lock_ptr;
e91467ec (Christian Borntraeger 2006-08-05 12:13:52 -0700 1931)?????????barrier();
c80544dc (Stephen Hemminger?????2007-10-18 03:07:05 -0700 1932)?????????if (lock_ptr != NULL) {
^1da177e (Linus Torvalds????????2005-04-16 15:20:36 -0700 1933)?????????????????spin_lock(lock_ptr);
^1da177e (Linus Torvalds????????2005-04-16 15:20:36 -0700 1934)?????????????????/*

with whitespace ignored, it gives:

$ git blame -w -L1927,+8 kernel/futex.c?
^1da177e (Linus Torvalds????????2005-04-16 15:20:36 -0700 1927)?
^1da177e (Linus Torvalds????????2005-04-16 15:20:36 -0700 1928)?????????/* In the common case we don't take the spinlock, which is nice. */
^1da177e (Linus Torvalds????????2005-04-16 15:20:36 -0700 1929) retry:
^1da177e (Linus Torvalds????????2005-04-16 15:20:36 -0700 1930)?????????lock_ptr = q->lock_ptr;
e91467ec (Christian Borntraeger 2006-08-05 12:13:52 -0700 1931)?????????barrier();
c80544dc (Stephen Hemminger?????2007-10-18 03:07:05 -0700 1932)?????????if (lock_ptr != NULL) {
^1da177e (Linus Torvalds????????2005-04-16 15:20:36 -0700 1933)?????????????????spin_lock(lock_ptr);
^1da177e (Linus Torvalds????????2005-04-16 15:20:36 -0700 1934)?????????????????/*

so there's an argument that get_maintainer.pl should by default
ignore whitespace changes.